"Welcome to nginx" and "Apache2 Ubuntu Default Page" default pages

[naupe]

I've created a post for this over in the /r/nginx Reddit community:
https://www.reddit.com/r/nginx/comments/bq6g77/welcome_to_nginx_and_apache2_ubuntu_default_page/

How come I'm getting the "Welcome to nginx!" and "Apache2 Ubuntu Default
Page" default pages? Where do I find these "default" pages in Nginx? The
default Apache page is very odd for ownCloud. Its running Apache for its
SSL, so the default page for it could be on the ownCloud VM. Meanwhile
Discourse does not have Nginx installed on it at all.

Can I redirect from one link to another with Nginx? For example, could I
redirect from https://oc.myreserveddns.com to
https://oc.myreserveddns.com/owncloud/index.php/login?

If you need more details, please let me know.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,284216,284216#msg-284216